This relates generally to imaging systems and, more particularly, to imaging systems with phase detection capabilities.
Modern electronic devices such as cellular telephones, cameras, and computers often use digital image sensors. Imager sensors (sometimes referred to as imagers) may be formed from a two-dimensional array of image sensing pixels. Each pixel receives incident photons (light) and converts the photons into electrical signals. Image sensors are sometimes designed to provide images to electronic devices using a Joint Photographic Experts Group (JPEG) format.
Some applications such as automatic focusing and three-dimensional (3D) imaging may require electronic devices to provide stereo and/or depth sensing capabilities. For example, to bring an object of interest into focus for an image capture, an electronic device may need to identify the distances between the electronic device and object of interest. To identify distances, conventional electronic devices use complex arrangements. Some arrangements require the use of multiple image sensors and camera lenses that capture images from various viewpoints. Other arrangements require the addition of lenticular arrays that focus incident light on sub-regions of a two-dimensional pixel array. Due to the addition of components such as additional image sensors or complex lens arrays, these arrangements lead to reduced spatial resolution, increased cost, and increased complexity.
Some electronic devices include both image pixels and phase detection pixels in a single image sensor. With this type of arrangement, a camera can use the on-chip phase detection pixels to focus an image without requiring a separate phase detection sensor. In a typical arrangement, phase detection pixels all have the same color and are arranged consecutively in a line in the pixel array. When phase detection pixels are arranged in this way, optical crosstalk becomes problematic. For example, optical crosstalk from a phase detection pixel into an adjacent normal image pixel may not match the crosstalk that would have occurred from the standard image pixel that would have occupied the phase detection pixel position. This could be due to the phase detection having a different microlens shape or the phase detection pixel being a different color from the normal color of a standard image pixel at that position. This arrangement also prevents the image sensor from obtaining the data that would be generated by standard image pixels. Compensating for the missing image pixel data can be difficult and can result in visual artifacts in the processed image.
It would therefore be desirable to be able to provide improved phase detection pixel arrangements for image sensors.